The companies Chemours, DuPont and Corteva announced on Friday they have agreed to pay more than $1 billion to settle claims that "forever chemicals" contaminated public US water systems.

The family of ubiquitous synthetic chemicals -- per- and polyfluoroalkyl substances, also known as PFAS -- linger in the environment and the human body, where they can cause serious health problems, and are found in everyday products including fast-food wrappers, makeup and carpeting.

In June, based on the latest science, the EPA issued health advisories that said the chemicals are much more hazardous to human health than scientists originally thought and are probably more dangerous even at levels thousands of times lower than previously believed.

The three chemical giants are facing thousands of lawsuits from across the country alleging the toxic chemicals were utilized in manufacturing and then polluted the environment.

In a statement, Dupont said it "has never manufactured PFOA or PFOS." CNN has reached out to the other companies for comment on the allegations, which they denied in a press release Friday.

The three companies said they have agreed to contribute a total of $1.185 billion to a settlement fund. Chemours will contribute 50 percent (about $592 million), and DuPont and Corteva will together contribute the remaining 50 percent, at about $400 million and $193 million, respectively.

The water systems serve the "vast majority" of the US population, the release said.

So far, the three companies reached an agreement in principle. A definitive agreement is expected to be finalized later this year in the US District Court for the District of South Carolina, the companies said.